Hmm, this is a problem we’ve never had reported before. There’s a couple of things to try before getting more diagnostics:
- reboot (just to ensure any locked files are released)
- in the Explorer type %APPDATA% and find the Steinberg/Dorico 3.5 subdirectory
- rename Dorico 3.5 (so that if you have any saved preferences those can be restored later)
- in Explorer type %TEMP% and find the Dorico 3.5 directory. Delete it
- run Dorico again